Novel materials and methods for water purification

ABSTRACT

A catalyst for the purification, e.g., disinfection, of water is disclosed. The catalyst of the invention comprises a substrate, a first metal, and at least one additional metal. The metals are codeposited on the substrate to form a unified structure. Methods of using the catalyst to disinfect water and devices for the purification of water are also disclosed.

RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional ApplicationSerial No. 60/142,828, entitled “Novel Materials and Methods for WaterDisinfection,” filed on Jul. 8, 1999, the entire contents of which arehereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] In developed countries, it is recognized that water should betreated to kill various microorganisms before being used municipally. Itis also recognized that water should be treated effectively before itcan be used in swimming pools, hot tubs and spas. Bodies of water suchas swimming pools, hot tubs and spas are highly susceptible to rapidmicro-organism growth. These bodies of water can rapidly becomeextremely hazardous to users, unless the water is effectively andcontinuously treated against micro-organisms.

[0003] One common method of treating water against microorganisms is toadd chlorine to render the water safe for human consumption and/or usein swimming pools, spas, etc. Normally, chlorine is added to the waterin the form of hypochlorite salt or chlorine gas. However, it has beenfound that chlorine has both an objectionable odor and can cause skinirritations and serious eye irritations to users.

[0004] Because of the objectionable physical properties of chlorine, anumber of alternate water treatment systems which operate withoutchlorine have been developed in recent years. One type of alternativewater treatment system is a system in which silver ions are added towater to kill the bacteria (see, for example, U.S. Pat. Nos. 4,608,247and 5,352,369). However, it has been found that, in many cases, systemsof this type are only partially effective, and amounts of chlorine mustbe added to water for complete disinfection.

SUMMARY OF THE INVENTION

[0005] In one embodiment, the invention pertains to a catalyst forpurifying water. The catalyst comprises a substrate, a first metal, andat least one additional metal. The first metal and the additional metalsare codeposited onto the substrate. In one further embodiment, thesubstrate is alumina, the first metal is silver, and the additionalmetals are selected from the group consisting of platinum, palladium,vanadium, molybdenum, or another transition metal or rare earth metal.Advantageously, the catalyst is capable of disinfecting water such thatit meets or exceeds water safety standards.

[0006] The invention also pertains to a catalyst for purifying water,comprising a substrate, silver, and palladium. The palladium and silverare codeposited onto the substrate and form a unified structure on thesurface of the substrate.

[0007] The invention also pertains to a method for purifying water, bycontacting water with the catalyst of the invention, such that the wateris purified. In one embodiment, purifying the water comprisesdisinfecting the water.

[0008] The invention also includes a method for inactivatingmicroorganisms in water. The method includes contacting the water with acatalyst of the invention, such that the bacteria are inactivated.

[0009] The invention also pertains to a device for purifying watercomprising the catalyst of the invention. In a further embodiment, thedevice includes a water inlet, water outlet and a housing which containsthe catalyst.

[0010] The invention also includes a packaged catalyst for thedisinfection of water. The packaged catalyst includes the catalyst ofthe invention, a container and instructions for using the catalyst forpurifying water.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIGS. 1A and 1B show a schematic diagram of a device for catalyticwater disinfection.

DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention pertains, at least in part, to methods,catalysts and devices useful for the purification, e.g., disinfection,of water. Techniques of water disinfection by a single metal, such assilver, are known. The known techniques exploit the catalytic ability ofsilver to react with oxygen dissolved in water to generate reactivechemical species that kill or inactivate bacteria, viruses and protozoa.

[0013] This invention improves on the known methods of disinfectingwater by single metal catalysis by incorporating at least one additionalmetal, either in its native metallic form or as its oxide. Incorporationof at least one additional metal improves the performance of thecatalyst by allowing the disinfection process to be faster, simpler,more effective, and less cumbersome.

[0014] I Definitions

[0015] Before further description of the invention, certain termsemployed in the specification, examples and appended claims are, forconvenience, collected here.

[0016] The term “codeposition” includes methods where two or more metalsare deposited on the substrate in such a manner that they form a unifiedstructure which comprises atoms of both of the metals.

[0017] Metals can be codeposited on the substrate by a number of methodsknown in the art including, for example, electro-codeposition, hydrogengas reduction, thermal reduction, and methods using chemical reducingagents such as sodium dithionate and ascorbic acid. In an embodiment,the metals are codeposited on the substrate such that they exist intheir ground states and/or capable of acting as proton/electronacceptors.

[0018] The term “disinfect” or “disinfecting” includes the killing orinactivation of pathogenic and other microorganisms, such as bacteria,viruses, fungi, and protozoa that pollute water supplies. Preferably,the catalyst of the invention disinfects water such that the resultingdisinfected water meets or exceeds standards for water purityestablished by various organizations and/or agencies including, forexample, the American Organization of Analytical Chemists (AOAC), theWorld Health Organization, and the United States EnvironmentalProtection Agency (EPA). Advantageously, water disinfected by thecatalysts and methods of the invention meets these without the additionof further disinfecting agents, e.g., chlorine or bromine.

[0019] The term “housing” includes any material in which the catalystcan be placed, such that the catalyst is capable of performing itsintended function, e.g., purifying water. Examples of housings for thecatalyst include porous bags, tubes, and other structures suitable forwater purification devices. The housing for the catalyst can be adaptedfor a specific use. For example, the housing may be tubular, for pumpingwater through the catalyst, or a porous bag for “flow through”applications.

[0020] The term “inactivate” or “inactivation” includes rendering amicroorganism non-pathogenic to humans or other animals, for example, bykilling the microorganisms. The microorganisms, such as bacteria, arekilled through interactions with reactive oxidative species generated bythe catalyst of the invention. For viruses, the oxidative species arebelieved to cause structural changes to the viral protein capsids whichcompromise the reproductive ability of the virus to inject geneticmaterial into host cells. The mechanism for bacteria and protozoa isidentical to that for chlorine and other oxidizers.

[0021] The term “kill rate” refers to the number of bacteria per volumeof water over time that the catalyst can effectively kill or inactivate.The kill rate can be determined by using the method outlined inExample 1. The kill rate of the catalyst of the invention is 1,000organisms/mL per fifteen seconds, or greater, 10,000 organisms/mL perfifteen seconds, or greater, 100,000 organisms/mL per fifteen seconds,or greater, or, advantageously, 1,000,000 organisms/mL per fifteenseconds, or greater.

[0022] The term “metal” includes elements or compounds that whendeposited on a substrate in combination with another metal are capableof disinfecting water. Examples of catalytic metals include transitionmetals, platinides, rare earth elements, and oxides of transitionmetals, platinides, and rare earth elements. In certain embodiments, themetals are not radioactive nor otherwise toxic to humans when present intrace amounts.

[0023] The term “microorganism” includes bacteria, fungi, protozoa,viruses and other biological entities and pathogenic species which canpollute water supplies. Examples of microorganisms include bacteria suchas Escherichia coli, Streptococcus faecalis, Legimella pneumophila,Yersinia enterocolitica, Staphylococcus aureus, Pseudomonas aeruginosaKlebsiella terrigena and Salmonella typhi. Examples of viruses includehepatitis A and other viruses which are advantageous to inactivate.Examples of fungi include many species, including those which are notpathogenic but are advantageously removed to improve the aestheticproperties of the water. Examples of protozoa include Enteroamoebae,Giardia, Cryptosporidium parvum etc.

[0024] The term “platinides” includes platinum, palladium, iridium andother elements which display similar electrochemical properties.

[0025] The term “purify” or “purifying” includes disinfection of thewater (e.g., killing or inactivation of microorganisms), as well as theoptional removal or inactivation of other contaminants in the water.Examples of contaminants include particulate matter, minerals, organicchemicals, etc.

[0026] The term “rare earth elements” include, for example, lanthanum,cerium, praseodymium, neodymium, promethium, samarium, europium,gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium,and lutetium.

[0027] The term “redox potential” refers to the ability of the catalystto transfer electrons to dissolved oxygen in the water source, thusforming reactive oxygen species. The redox potential of a catalyst canbe determined by methods known in the art. One example of a method usedto determine the redox potential of a catalyst is to exposeN,N-diethyl-1,4-phenylenediamine (DPD, Fischer Scientific) to thecatalyst in oxygen free water. The redox potential of the catalyst canalso be determined through the use of electronic devices known in theart, for example, through the use of commercially available electronicredox electrodes.

[0028] The term “substrate” includes any solid onto which the catalystof the invention can be deposited, such that the catalyst is able toperform its intended function, e.g., disinfect water. In an embodiment,the substrate has a high surface area, e.g., is highly porous. Examplesof substrates include metal oxides, such as, for example, alumina,silica or titanium dioxide.

[0029] The term “transition metal” includes, for example, scandium,titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper,zinc, gallium, germanium, ytterbium, zirconium, niobium, technetium,ruthenium, rhodium, palladium, molybdenum, silver, cadmium, indium, tin,antimony, hafnium, tantalum, tungsten, rhenium, osmium, iridium,platinum, gold, mercury, thallium, etc. Preferred transition metalsinclude those capable of electron donation and/or electron accepting, aswell as those which are not fatally toxic in trace amounts andnon-radioactive. Examples of advantageous transition metals includesilver, palladium, platinum, vanadium, and molybdenum.

[0030] The term “unified structure” includes structures which allow thecatalyst to perform its intended function, e.g., disinfecting water.Advantageously, the atoms of each of the metals are codeposited on thesubstrate, such that they are evenly dispersed over the surface of thesubstrate. For example, the metal present in lower quantities (the“additional metal”, e.g., palladium) is integrated in to the metallattice of the metal which is present in larger quantities (the “firstmetal”, e.g., silver).

[0031] The term “water safety standards” includes standards issued bythe American Organization of Analytical Chemists (AOAC, International),for water consumption by humans, for water consumption by animals, andswimming. The standards given by the AOAC, International are 1,000,000kill of E. coli per mL in 15 fifteen seconds. Other water safetystandards include those issued by the World Health Organization (WHO,see Guidelines for Drinking Water Quality) and the United StatesEnvironmental Protection Agency (EPA, See Publication No. 570/9/76-003).The water purified by the methods of the invention meets both the WHOand the EPA standards for potable water, as well as the standardsestablished for recreational water (swimming pools, spas, etc.).

[0032] II Catalysts of the Invention

[0033] In one embodiment, the invention pertains to a catalyst fordisinfecting water. The catalyst comprises a substrate, a first metal,and at least one additional metal. Advantageously, the first metal andthe additional metals are codeposited on the substrate, such that theyform a unified structure. The presence of one or more additional metals,such as palladium, significantly increases the efficacy of the catalyst.Examples of substrates include, for example, metal oxides such asalumina.

[0034] Without being bound or limited by theory, it is believed that atleast one of the metals may function as an electron acceptor, while theother may function as proton acceptor. It is further believed thatincreased efficiency of electron transfer on the surface of the catalystleads to enhanced ability of the catalyst to generate reactive speciesand, therefore, purify, e.g., disinfect, water. For example, in oneembodiment, the catalyst comprises an alumina substrate onto which iscodeposited silver (“the first metal”) and palladium (“the additionalmetal”). The electron accepting silver atoms complex with the loneelectron pairs on oxygen (dissolved in the water) to function as anoxygen bridge. This oxygen bridge is a powerful reactive oxidativespecies, and is very unstable. The proton accepting palladium serves tostabilize the complex, thereby enhancing the ability of the catalyst togenerate reactive oxygen species that kill microorganisms in water, orthat convert harmful, toxic and/or reactive organic compounds containedin water to less harmful, less toxic and/or less reactive compounds.

[0035] Examples of metals codeposited on the substrate includetransition metals, platinides, rare earth metals, and oxides oftransition metals, platinides, and rare earth metals. In one embodiment,the first metal is silver. Silver, a transition metal, has already beenshown previously to catalytically induce water disinfection byconverting dissolved oxygen, and other available oxidizers, intoreactive species which inactivate microorganisms.

[0036] The first metal is present in the catalyst in an amount greaterthan the amount of the additional metal. The amount of the first metalis selected such that the catalyst is capable of performing its intendedfunction, e.g., disinfecting water. Generally, for example, the amountof the first metal, e.g., silver, is present in an amount ranging fromabout 0.1% to about 10%, about 0.25% to about 5%, or about 0.25% toabout 3%, or about 0.5% to about 3%, or about 0.5% to about 2%, or about1.2% of the total weight of the catalyst.

[0037] The additional metals of the catalyst are selected, generally,for their ability to change their valence states, and effectivelyparticipate in the catalytic disinfection process of the water. Examplesof additional metals include palladium, platinum, vanadium, andmolybdenum. In one embodiment, at least one of the additional metals ispresent as its oxide.

[0038] The additional metals are present in the catalyst in an amountless than the amount of the first metal. The amount of the additionalmetals are selected such that the catalyst is capable of performing itsintended function, e.g., disinfecting water. Generally, for example, theamount of an additional metal, e.g., palladium, is present in amountsabout 1 ppm to about 100 ppm, about 1 ppm to about 75 ppm, about 1 ppmto about 60 ppm, about 1 ppm to about 50 ppm, about 1 ppm to about 40ppm, about 1 ppm to about 30 ppm, about 1 ppm to about 20 ppm, about 1to about 15ppm, about 2 ppm to about 15 ppm, about 2 ppm to about 14ppm, about 2 ppm to about 13 ppm, about 2 ppm to about 12 ppm, about 2ppm to about 11 ppm, about 2 ppm to about 10 ppm, and about 1 ppm bytotal weight of the catalyst. In percent weight, the additional metal ispresent in the catalyst in an amount, generally, about 1×10⁻⁴% to about1×10⁻²%, about 1×10⁻⁴% to about 7.5×10⁻³%, about 1×10⁻⁴% to about6×10⁻³%, about 1×10⁻⁴% to about 5.0×10⁻³%, about 1×10⁻⁴% to about4.0×10⁻³%, about 1×10⁻⁴% to about 3.0×10⁻³%, about 1×10⁻⁴% to about2.0×10⁻³%, about 1×10⁻⁴% to about 15×10⁻⁴%, about 2×10⁻⁴% to about15×10⁻⁴%, about 2×10⁻⁴% to about 14×10⁻⁴%, about 2×10⁻⁴% to about13×10⁻⁴%, about 2×10⁻⁴% to about 12×10⁻⁴%, about 2×10⁻⁴% to about11×10⁻⁴%, about 2×10⁻⁴% to about 10×10⁻⁴%, and about 1×10⁻³% of thetotal weight of the catalyst.

[0039] In a second embodiment, the metals of the catalyst are selectedsuch that the catalyst has a redox potential which allows it to performits intended function, e.g., disinfect water. The redox potential of thecatalyst can be measured using standard techniques known in the art,such as using a DPD indicator in oxygen free distilled water. Thecatalyst of the invention preferably has a redox potential of 40 mV/g orgreater, 50 mV/g or greater, 60 mV/g or greater, 70 mV/g or greater, 80mV/g or greater, 90 mV/g or greater, 100 mV/g or greater, 110 mV/g orgreater, 120 mV/g or greater, or, advantageously, 130 mV/g or greater.The redox potential of the catalysts of the invention are particularlysurprising in comparison to the redox potential of conventionalcatalysts, such as those disclosed in U.S. Pat. Nos. 5,660,802,4,504,287, 4,608,247, and 5,352,369. The catalysts disclosed in thesepatents have a redox potential of only about 30 mV/g which isineffective to inactivate bacteria without additional support from otherwater disinfecting methods or agents.

[0040] The metals of the catalyst are advantageously selected such thatthe catalyst has a kill rate for bacteria such as 1,000 organisms/mL perfifteen seconds or more, 10,000 organisms/mL per fifteen seconds ormore, 100,000 organisms/mL per fifteen second or more, or,advantageously, 1,000,000 organisms/mL per fifteen seconds or more. In afurther embodiment, the kill rate of bacteria and/or othermicroorganisms meets or exceeds water safety standards, such as thosepublished by AOAC International. The kill rates of the present inventionare surprising over conventional silver on alumina catalysts used todisinfect water, because the conventional catalysts have a much lowerkill rate(100 to about 1,000 organisms/mL per fifteen seconds), after asingle pass over the catalyst. The conventional silver catalysts do notmeet the AOAC, International standards, generally, and, hence, usuallyrequire additional purification methods or agents.

[0041] The catalyst of the invention may be formulated as a granularsolid, as a fine powder, or as a wet slurry. The exact formulation willdepend on the method and manner of manufacture, as well as the desireduse of the catalyst.

[0042] III. Methods of the Invention

[0043] The invention also pertains to a method for purifying water. Themethod includes contacting the water with a catalyst of the invention,such that the water is purified. Without being bound or limited bytheory, it is believed that the catalyst reacts with dissolved oxygen inthe water to generate a highly reactive and powerful oxidative species.

[0044] Thus, in one embodiment, the invention is a method fordisinfecting water. The disinfection of the water may comprise,advantageously, the killing or inactivation of bacteria, protozoa,viruses, fungi, and other pathogenic and non-pathogenic microorganisms.

[0045] In a further embodiment, the method may also comprise passing thewater through one or more filters to remove other particles andcontaminants which are not removed by interactions with the catalyst.For example, in yet another embodiment, the method further comprisespassing the water through a charcoal filter before or after disinfectionwith the catalyst of the invention to remove non-bacterial contaminantspresent in the water.

[0046] In another embodiment, the disinfected water meets or exceedswater safety standards, such as those established by the AOAC,International, WHO and EPA. Preferably, the water disinfected by themethods of the invention do not require additional agents orpurification steps to meet or exceed the requirements for inactivationof microorganisms in water supplies.

[0047] In an advantageous embodiment, the invention pertains to a methodfor inactivating bacteria in water. The method includes contacting thewater with a catalyst. The catalyst comprises a substrate (e.g.,alumina), a first metal (e.g., silver), and at least one additionalmetal (e.g., palladium). The metals are codeposited onto said substrate,such as to form a unified structure.

[0048] In yet another embodiment, the invention is a method forpurifying water by converting harmful, toxic and/or reactive organiccompounds contained in the water to less harmful, less toxic and/or lessreactive compounds.

[0049] IV. Water Purification Devices of the Invention

[0050] In another embodiment, the invention is directed to a device forpurifying water. In a preferred embodiment, the device is used todisinfect water. The device comprises the catalyst of the invention, asdescribed above. In another embodiment, the device further comprises awater inlet, a water outlet, and a housing containing the catalyst ofthe invention. The device may also include other filters and featureswhich allow or enhance the ability of the device to perform its intendedfunction, e.g., disinfect water. The device may include, in certainembodiments, one or more filters, such as charcoal filters, to removeimpurities, particles, and other non-bacterial contaminants present inthe water.

[0051] One embodiment of a water disinfecting device of the invention isshown in FIGS. 1A and 1B. In FIG. 1A, the water inlet (10) is connectedto the housing (20), which is connected to the water outlet (30). Thearrow indicates the direction of the flow of the water. FIG. 1B is acutaway view of the device which shows that the catalyst (40) is locatedinside the housing (20). Water flows through the water inlet (10), tothe housing (20) where it comes into contact with the catalyst (40). Thewater then exits the device through the water outlet (30).

[0052] In a further embodiment, the catalyst is incorporated into one ormore filter beds. The undisinfected water is filtered through the bedsand is disinfected when it comes into contact with the catalyst. Thewater can be purified by a single pass through the filter bed or througha series of filter beds. Alternatively, water can be recirculatedthrough one or more filter beds repeatedly.

[0053] In another embodiment, the catalyst is deposited on the surfaceof a container, pipe, tube, or other another surface to which the wateris exposed. The catalyst can completely coat the surface that the watercomes into contact with, or it may only cover a portion of the surfacethe water contacts.

[0054] In another embodiment, the catalyst is incorporated into acapsule or packet which can be agitated within the water sample. Forexample, the catalyst is placed in a porous packet which is placed inthe water to be disinfected and agitated, such that the water isdisinfected. Advantageously, the porous package is portable.

[0055] In another embodiment, the device for water disinfectioncomprises a housing containing the catalyst, and a water inlet and awater outlet, through which water can flow. In one embodiment, thedevice is suitable for home use. For example, the device may beconstructed so that it can be attached to a faucet, hose, spigot, wellor other home or farm water source such that the water is immediatelypurified through the device before being consumed or used. In anembodiment, the device is constructed such that it is portable andsuitable for travel. In a further embodiment, the device is designedsuch that it is suitable for farm use. For example, the device isadvantageously designed such that it can disinfect water for use inanimal drinking troughs.

[0056] In another embodiment, the water disinfection device is suitablefor killing bacteria and other microorganisms located in a confined areaof water, such as a pool, spa, hot tub, pond, etc. Examples of waterpurification devices know in the art include those described in U.S.Pat. Nos. 5,660,802, and 4,504,387, which are expressly incorporatedherein by reference.

[0057] The water purifier of U.S. Pat. No. 5,660,802 comprises a waterinlet, a water outlet, and a purification unit that kills the bacteriain the water. It can be used for killing bacteria in a confined area ofwater in accordance with the methods of the invention by replacing itsconventional catalyst with the catalyst of the invention.

[0058] U.S. Pat. No. 4,504,387 discloses a water purification system foruse with a pool or the like in which a small quantity of water iscontinually withdrawn from the pool and recycled and disinfected. Thiswater purification system can also be improved by substituting itsconventional catalyst with the catalyst of the present invention.

[0059] In a further embodiment, the water purification device issuitable for large scale purification of water, e.g., municipal watersources.

[0060] The invention also pertains to a packaged catalyst for thedisinfection of water. The packaged catalyst includes the catalyst ofthe invention, a suitable container for the catalyst (e.g., aflow-through bag, a box, a vial, etc.), and instructions for using thecatalyst for the disinfection of water.

EXEMPLIFICATION OF THE INVENTION

[0061] The invention is further illustrated by the following examplesthat should not be construed as limiting.

EXAMPLE 1

[0062] A batch of water purification catalyst was prepared by reducingsilver and palladium salts on a bed of alumina substrate.

[0063] Alumina (1,000 g) (Alcoa CPN 8-14 mesh) was used as thesubstrate. Eighteen grams of silver nitrate (99.95% commercial grade)and 2.5 milligrams of palladium nitrate (Fisher Scientific AS standardgrade) were thoroughly mixed with the alumina substrate. The silvernitrate and the palladium nitrate were coreduced to a metallic coatingon the alumina substrate by aqueous phase reducing agents at ambienttemperature. The resulting material was then dried for 3 hours at 450°F.

[0064] The efficacy of the catalyst was then measured and compared witha conventional silver catalyst.

[0065] A sample of E. coli (ATCC#25922) was incubated at 37° C. onTryptic Soy Agar (Difco) and harvested. The bacteria were diluted to aworking concentration of 10⁵ to 10⁶ organisms per milliliter in buffersolution. The buffer solution consisted of tap water previouslydechlorinated with sodium thiosulfate, buffered to a pH of 7.2 withphosphate buffer.

[0066] The bacterial solution was pumped at 19 liters/min through acontrol catalyst bed which contained 200 grams of silver/aluminacatalyst. The silver/alumina catalyst can be prepared by the methodoutlined above. The bacterial solution was also pumped at the samevelocity through a catalyst bed which contained 200 grams of thesilver/palladium/alumina catalyst. Samples of the water were collectedafter discharge from each of the catalyst beds.

[0067] The samples were then assayed for viable bacteria using themembrane filtration test as described in ‘Standard Methods for theExamination of Water and Wastewater.’ (17^(th) ed. 1989, American PublicHealth Association (APHA), American Water Works Association (AWWA),Water Pollution Control Federation (WPCF)). Temperature and dissolvedoxygen were consistently maintained during the experiments.

[0068] The results from the experiment are shown in Table 1. The samplesused for the table were drawn 60 seconds into the pumping cycle. TABLE 1E. coli Concentration After Exposure to After Exposure to InitialAlumina/Silver Alumina/Silver/ Dilution Concentration Catalyst PalladiumCatalyst 1:100,000 57 0 0 1:10,000 >300 4 0 1:1,000 NR 53 0 1:100NR >300 7 1:10 NR NR 62

[0069] Samples were also evaluated with the palladium/silver/aluminacatalyst after 30 and 120 second pumping periods. No significantvariation was found compared to the 60 second pumping period sample(sample dilution of 1:1000 showed 1 cfu (colony forming unit) at 30seconds and 0 cfu at both 60 and 120 seconds).

[0070] The results indicate the alumina/silver/palladium catalyst has animproved efficiency for killing E. coli of at least a factor of ten overthe previously known silver/alumina catalyst.

EXAMPLE 2

[0071] This example shows that changing the ratio of the metals on thecatalyst affects the ability of the catalyst to inactivate the bacteria.The amount of palladium in the catalyst was increased from 2.5 mg/kg inthe previous example to 10 mg/kg. A catalyst which contained only silverand alumina was used as the control. The catalyst was prepared using thesame method as given in Example 1.

[0072] Table 2 shows data from kill studies using E. coli and theStandard Methods membrane filtration methodology used in Example 1.TABLE 2 Initial Dilution Concentration Control Pd Catalyst 1:100,000 230 4 <1 1:1,000 TNTC 294 <1 1:1,000 TNTC NR <1 1:100 NR TNTC <1 1:100 NRNR <1 1:10 NR NR <1

[0073] The tables show that the alumina/silver/palladium catalyst of theinvention has high kill rates of E. coli that are capable of beingduplicated in separate experiments. For each of the dilutions, thecatalyst was able to kill effectively all the bacteria present incontrast to the known catalyst.

EXAMPLE 3

[0074] Table 3 below represents the results of four replicates ofbacterial kill studies using the catalyst of Example 2. The results wereconsistent among the four replicates; i.e., no live bacteria weredetected in water samples treated with the catalyst of Example 2.

[0075] In each of the replicate studies, bacteria were introduced from2, 24 hour Tryptic Soy Agar slants into a container with 20 liters ofdechlorinated tap water and a pump. The water temperature was 30° C. Thestart sample was drawn directly from the water in the container with apipette. A sample was then drawn from the container using the pumpwithout the catalyst in place. The water was pumped through the catalystbed at a rate of about 19 liters per minute. The second sample was thendrawn from the container using the pump with the catalyst in place. Theresults are as shown in Table 3. All values are given as colony formingunits (cfu) per 100 ml of sample. TNTC stands for too numerous to count.<1 is statistically 0. TABLE 3 Control Dilution Start (w/o catalyst)With Catalyst 1:1,000,000 511 cfu NR NR 1:100 TNTC TNTC <1 1:10 NR TNTC<1 1:1 NR TNTC <1

[0076] Table 3 shows that the catalyst was effective to kill essentiallyall the bacteria present in the container. The water purified by thepalladium/silver/alumina catalyst used in Examples 2 and 3 meets thestandards for water purity issued by the EPA and the WHO at eachdilution.

[0077] Incorporation by Reference

[0078] The entire contents of all patents, published patent applicationsand other references cited herein are hereby expressly incorporatedherein in their entireties by reference.

[0079] Equivalents

[0080] Those skilled in the art will recognize, or be able to ascertain,using no more than routine experimentation, many equivalents to specificembodiments of the invention described specifically herein. Suchequivalents are intended to be encompassed in the scope of the followingclaims.

1. A catalyst for purifying water comprising a substrate, a first metal,and at least one additional metal, wherein said first metal and saidadditional metal are codeposited onto said substrate.
 2. The catalyst ofclaim 1, wherein said purifying comprises disinfecting said water bykilling of microorganisms contained therein.
 3. The catalyst of claim 1,wherein said substrate is a metal oxide.
 4. The catalyst of claim 3,wherein said substrate is alumina.
 5. The catalyst of claim 1, whereinsaid first metal is selected from the group consisting of transitionmetals, platinides, rare earth metals, and oxides of transition metals,platinides, or rare earth metals.
 6. The catalyst of claim 5, whereinsaid first metal is a transition metal.
 7. The catalyst of claim 6,wherein said first metal is copper, silver or gold.
 8. The catalyst ofclaim 7, wherein said first metal is silver.
 9. The catalyst of claim 1,wherein said first metal is an oxide of a transition metal, a platinide,or a rare earth metal.
 10. The catalyst of claim 1, wherein saidadditional metal is selected from the group consisting of transitionmetals, platinides, rare earth metals, and oxides of transition metals,platinides, or rare earth metals.
 11. The catalyst of claim 10, whereinsaid additional metal is a transition metal.
 12. The catalyst of claim11, wherein said additional metal is platinum, palladium, molybdenum, orvanadium.
 13. The catalyst of claim 12, wherein said additional metal ispalladium.
 14. The catalyst of claim 10, wherein said additional metalis an oxide of a transition metal, a platinide, or a rare earth metal.15. The catalyst of claim 9, further comprising one or more additionalmetal oxides.
 16. The catalyst of claim 1, wherein said catalyst has aredox potential of 100 mV/mg or greater.
 17. The catalyst of claim 16,wherein said catalyst has a redox potential of 120 mV/mg or greater. 18.The catalyst of claim 17, wherein said catalyst has a redox potential of130 mV/mg or greater.
 19. A catalyst for purifying water comprising asubstrate, silver, and palladium, wherein palladium and silver arecodeposited onto said substrate and wherein said palladium and saidsilver form a unified structure on the surface of said substrate. 20.The catalyst of claim 19, wherein said substrate is a metal oxide. 21.The catalyst of claim 20, wherein said substrate is alumina.
 22. Thecatalyst of claim 19, wherein silver comprises about 0.1% to about 3.0%of the weight of the catalyst.
 23. The catalyst of claim 22 whereinsilver comprises about 0.5% to about 3.0% of the weight of the catalyst.24. The catalyst of claim 23, wherein silver comprises about 0.5% toabout 2.0% of the weight of the catalyst.
 25. The catalyst of claim 24,wherein silver comprises about 1.2% of the catalyst.
 26. The catalyst ofclaim 19, wherein palladium comprises about 1×10⁻⁴ to about 1×10⁻²% ofthe weight of the catalyst.
 27. The catalyst of claim 26, whereinpalladium comprises about 1×10⁻⁴ to about 6×10⁻³% of the weight of thecatalyst.
 28. The catalyst of claim 27, wherein palladium comprisesabout 1×10⁻⁴ to about 5×10⁻³% of the weight of the catalyst.
 29. Thecatalyst of claim 28, wherein palladium comprises about 1×10⁻⁴ to about2×10⁻³% of the weight of the catalyst.
 30. A method for purifying water,comprising contacting water with a catalyst, wherein said catalystcomprises a substrate, a first metal, and at least one additional metal,and wherein said first metal and said additional metal are codepositedonto said substrate, to purify thereby said water.
 31. The method ofclaim 30, wherein said purifying comprises disinfecting said water bykilling of microorganisms contained therein.
 32. The method of claim 30,wherein said substrate is a metal oxide.
 33. The method of claim 32,wherein said substrate is alumina.
 34. The method of claim 30, whereinsaid first metal is selected from the group consisting of transitionmetals, platinides, rare earth metals, and oxides of transition metals,platinides, or rare earth metals.
 35. The method of claim 34, whereinsaid first metal is a transition metal.
 36. The method of claim 35,wherein said first metal is copper, silver or gold.
 37. The method ofclaim 36, wherein said first metal is silver.
 38. The method of claim20, wherein said first metal is an oxide of a transition metal, aplatinide, or a rare earth metal.
 39. The method of claim 30, whereinsaid additional metal is selected from the group consisting oftransition metals, platinides, rare earth metals, and oxides oftransition metals, platinides, or rare earth metals.
 40. The method ofclaim 39, wherein said additional metal is a transition metal.
 41. Themethod of claim 40, wherein said additional metal is platinum,palladium, molybdenum, or vanadium.
 42. The method of claim 41, whereinsaid additional metal is palladium.
 43. The method of claim 49, whereinsaid additional metal is oxide of a transition metal, a platinide, or arare earth metal.
 44. The method of claim 38, further comprising one ormore additional metal oxides.
 45. The method of claim 30, wherein saidcatalyst has a redox potential of 100 mV/mg or greater.
 46. The methodof claim 45, wherein said catalyst has a redox potential of 120 mV/mg orgreater.
 47. The method of claim 46, wherein said catalyst has a redoxpotential of 130 mV/mg or greater.
 48. The method of claim 31, whereinsaid catalyst has a kill rate of 1,000 organisms/mL per fifteen seconds,or greater of microorganisms contained in said water.
 49. The method ofclaim 31, wherein said catalyst has a kill rate of 10,000 organisms/mLper fifteen seconds, or greater of microorganisms contained in saidwater.
 50. The method of claim 31, wherein said catalyst has a kill rateof 100,000 organisms/mL per second, or greater of microorganismscontained in said water.
 51. The method of claim 30, wherein saidcatalyst comprises an alumina substrate, silver, and palladium, whereinsaid silver and said palladium are codeposited onto said substrate. 52.The method of claim 31, wherein said microorganisms are selected fromthe group consisting of bacteria, viruses, fungi, protozoa, and mixturesthereof.
 53. The method of claim 62, wherein said microorganism isbacteria.
 54. The method of claim 53, wherein said bacteria is selectedfrom the group consisting of Escherichia coli, Streptococcus faecalis,Legimella pneumophila, Yersinia enterocolitica, Staphylococcus aureus,Pseudomonas aeruginosa, Klebsiella terrigena, Salmonella typhi andmixtures thereof.
 55. The method of claim 51, wherein the disinfectedwater meets or exceeds water safety standards for potable water.
 56. Themethod of claim 55, wherein said disinfected water meets or exceedswater safety standards for potable water without an additional waterdisinfecting step.
 57. The method of claim 30, further comprisingcontacting the water through a charcoal filter.
 58. The method of claim57, wherein said water is contacted with said charcoal filter prior tocontact with said catalyst.
 59. A method for inactivating microorganismsin water, comprising contacting the water with a catalyst, wherein saidcatalyst comprises a substrate, a first metal, and at least oneadditional metal, wherein said first metal and said additional metal arecodeposited onto said substrate, such that said bacteria areinactivated.
 60. The method of claim 59, wherein said substrate isalumina.
 61. The method of claim 59, wherein said first metal is silver.62. The method of claim 59, wherein said additional metal is selectedfrom the group consisting of palladium, platinum, vanadium, andmolybdenum.
 63. The method of claim 62, wherein said additional metal ispalladium.
 64. The method of claim 59, wherein said microorganisms arebacteria selected from the group consisting of Escherichia coli,Streptococcus faecalis, Legimella pneumophila, Yersinia enterocolitica,Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella terrigena,Salmonella typhi, and mixtures thereof.
 65. A device for purifying watercomprising a catalyst, wherein said catalyst comprises a substrate, afirst metal, and at least one additional metal, wherein said first metaland said additional metal are codeposited onto said substrate.
 66. Thedevice of claim 65 which further comprises a filter, wherein said filtercontains said catalyst.
 67. The device of claim 65, wherein saidpurifying comprises disinfecting said water by killing of microorganismscontained therein.
 68. The device of claim 67, wherein said catalystcomprises an alumina substrate, silver, and palladium, wherein saidsilver and said palladium are codeposited onto said substrate.
 69. Thedevice of claim 67, wherein said device is portable.
 70. The device ofclaim 65, which further comprises a housing surrounding said catalyst, awater inlet and a water outlet.
 71. A packaged catalyst for thedisinfection of water comprising a catalyst, a container for saidcatalyst, and instructions for using said catalyst for the disinfectionwater, wherein said catalyst comprises a substrate, a first metal, andat least one additional metal, wherein said first metal and saidadditional metal are codeposited onto said substrate.
 72. The catalystof claim 1, wherein said purification comprises converting harmful,toxic and/or reactive organic compounds contained in the water to lessharmful, less toxic and/or less reactive compounds.
 73. The method ofclaim 30, wherein said purification comprises converting harmful, toxicand/or reactive organic compounds contained in the water to lessharmful, less toxic and/or less reactive compounds.